Hydrorefining of petroleum crude oil



United States Patent 3,317,421 HYDROREFINING 0F PETROLEUM CRUDE 01L William K. T. Gleim, Island Lake, and John G. Gatsis, Des Plaines, Ill., assignors to Universal Oil lroducts Company, Des Plaines, 11]., a corporation of Delaware No Drawing. Filed Sept. 25, 1964, Ser. No. 399,367 5 Claims. (Cl. 208-264) The present invention relates to a process for hydrorefining of petroleum crude oil, heavy vacuum gas oil, tar sands oil, crude tower bottoms, vacuum tower bottoms product, visbreakerproduct effluent, heavy cycle stocks, and other highwboiling hydrocarbon fractions and/or distillates. More specifically, the present invention is directed toward a captalytic, slurry-type process for hydrorefining heavy hydrocarbonaceous material severely contaminated by the inclusion therein of excessive quantities of deleterious substances.

In one of its embodiments, the present invention in volves a process for effecting the decontamination, or hydrorefining, of a heavy hydrocarbon charge stock for the purpose of effecting the destructive removal of nitrogenous and sulfurous compounds, and particularly for the conversion of the pentane-insoluble portion of such charge stock into more valuable pentane-soluble' hydrocarbon products. Crude petroleum oil, and other heavy hydrocarbon fractions and/or distillates, which boil at temperatures greater than the gasoline and middle-distillate boiling ranges, generally contain nitrogenous and sulfurous compounds in large quantities. In addition, these high-boiling hydrocarbon fractions contain quantities of metallic contaminants which exhibit the tendency to exert detrimental effects upon a catalyst utilized in a process to which the crude oil, or portion thereof is ultimately subjected. The more common of such metallic contaminants are nickel and vanadium, although other metals including iron, lead, arsenic, copper, etc., may be present. Although the metallic contaminants may exist in a variety of forms, they are usually found as organo-metallic compounds of high molecular weight, such as metal porphyrins and the various derivatives thereof. Notwithstanding the total concentration of these metallic contaminants is relatively small, often less than about p.p.m., calculated as the elemental metal, subsequent processing techniques are easily adversely alfected thereby. For example, when a hydrocarbon charge stock, containing metals in excess of about 10.0 p.p.m., is subjected to a cracking process for the purpose of producing lower-boiling, normally liquid hydrocarbons, the metals become deposited upon the catalyst, steadily increasing in quantity until such time as the composition of the catalytic composite is changed to the extent that undesirable results are obtained.

In addition to the contaminating influences, exemplified by nitrogenous and sulfurous compounds, and organometallic complexes, crude oils and other heavy hydrocarbon fractions generally consist of a significant quantity of high-boiling, pentane-insoluble material. For example, a full boiling range Wyoming sour crude oil, having a gravity of 232 API at 60 F., is not only contaminated by about 2.8% by weight of sulfur, approximately 2,700 p.p.m. of total nitrogen, a total of about 100 p.p.m. of metallic porphyrins (computed as elemental nickel and vanadium), but contains a pentane-insoluble asphaltenic fraction in an amount of about 8.39% by weight. Similarly, a crude tower bottoms product, having a gravity, API at 60 F., of 14.3, is contaminated by the presence of 3.0% by weight of sulfur, 3,830 p.p.m. of nitrogen, about 85 p.p.m. of total metals and about 10.83% by Weight of asphaltenic compounds. A much 3,3l7,4 2l Patented May 2, 1967' more difiicult charge to convert into normally liquid hydrocarbons is a vacuum tower bottoms product having a gravity, API at 60 F., of 7.0, containing more than 6,000 p.p.m. of nitrogen, about 4.0% by weight of sulfur, over 450 p.p.m. of metallic contaminants, and about 24.0% by weight of pentane-insoluble asphaltenic material. This asphaltenic material consists of high molecular weight hydrocarbons which are considered to be cokeprecursors having the tendency to become immediately deposited within the reaction zone and other process equipment, and onto the catalytic composite in the form of a gummy, heavy hydrocarbonaceous residue. Since this in effect constitutes a large loss of charge stock, it is economically desirable to convert such asphaltenes into pentane-soluble liquid hydrocarbon products. Furthermore, the presence of excessive quantities of asphaltenes appears to inhibit the activity of a hydrorefining catalyst with respect to its ability to eifect the removal of sulfur and nitrogen by conversion thereof to hydrogen sulfide, ammonia and hydrocarbons.

The object of the present invention is to provide a more efiicient process for hydrorefining, or decontaminating petroleum crude oil and other heavy hydrocarbon fractions, than those processes currently employed. A fixed-bed catalytic process, or a fixed-fluidized bed process is virtually precluded due to the difliculty in maintaining the catalyst in an active condition. Various moving-bed processes, employing catalytically active metallic components composited with a highly refractory inorganic oxide material, are extremely erosive, thereby causing plant maintenance to become difficult and expensive. The present invention teaches the preparation of a colloidally dispersed unsupported catalytic component useful in a slurry process. The catalyst of the present invention is particularly advantageous for effecting the conversion of pentane-insoluble material into pentane-soluble liquid hydrocarbons, while simultaneously converting a high percentage of the nitrogenous and sulfurous compounds into ammonia, hydrogen sulfide and hydrocarbons. The process of the present invention yields a liquid hydrocarbon product substantially free from pentane-insoluble asphaltenes, and significantly reduced in nitrogen and sulfur concentration to the extent that a subsequent fixed-bed catalytic process, intended to result in an ultra-clean hydrocarbon product, becomes economically feasible.

In a broad embodiment, the present invention relates to a process for hydrorefining a hydrocarbon charge stock, which process comprises admixing said charge stock with a lead salt selected from the group consisting of salts of fatty acids, polyfunctional acids and aromatic acids, reacting the resulting colloidal suspension with hydrogen at a temperature above about 225 C., removing a metal-containing sludge from the reaction efliuent and recovering a hydrorefined liquid product.

In another =br0ad embodiment, the present invention encompasses a process for hydrorefining a hydrocarboncharge stock, which process comprises admixing said charge stock with lead acetate, reacting the resulting mixture with hydrogen at a temperature above about 225 C., removing a metal-containing sludge from the reaction product eflluent and recovering a hydrorefined liquid product.

A more limited embodiment of the present invention ing a metal-containing sludge from the resulting reaction product effluent and recovering a hydrorefined liquid product.

From the foregoing embodiments, it is readily ascertained that the method of the present invention involves a preparation of a colloidally-dispersed catalytic component within the hydrocarbon charge stock from which the contaminating influences are to be removed. The colloidally dispersed catalytic component is a lead salt, and particularly lead acetate. The quantity of lead acetate utilized is such that the colloidal suspension or dispersion, resulting upon admixture with the hydrocarbon charge stock, comprises from about 1.0% to about 30.0% by weight, calculated as if the lead existed in the elemental state. Lower concentrations of lead acetate may be employed, to achieve acceptable results, and lie within the range of from about 1.0% to about 10.0% by weight. Other suitable lead salts include salts of other fatty acids such as propionic acid, butyric acid, stearic acid and oleic acid, salts of aromatic acids including benzoic acid and phthalic' acid, etc. Lead acetate is especially preferred due to its ability to decrease the concentration of snlfurous and nitrogenous compounds While simultaneously converting a high percentage of pentane-insoluble asphaltenes.

Briefly, the process is effected by initially admixing the desired quantity of lead acetate with the hydrocarbon charge stock in an amount such that the resulting colloidal suspension, or dispersion, contains from about 1.0% to about 10.0% by weight of lead, calculated as the element thereof. For this purpose, it is preferred that the lead acetate be in the form of a solution, which facilitates the formation of the colloidal suspension. Suitable solvents include methanol, isopropyl alcohol, isobutyl alcohol, isoamyl alcohol, etc., and various aromatic hydrocarbons including benzene, toluene and xylene. The solution of lead acetate is added dropwise to the hydrocarbon charge stock, and at a temperature at which the solvent is immediately removed by distillation. The resulting coloidal dispersion is then passed into a suitable reaction zone maintained at a temperature within the range of from about 225 C. to about 500 C. and under a hydrogen pressure of about 500 to about 5,000 p.s.i.g. Although the presence of added hydrogen sulfide in the hydrogen atmosphere has been found to enhance the catalytic activity of other metals which may be dispersed within the hydrocarbon charge stock, including metallic salts, betadiketone complexes, heteropoly acids, etc., added hydrogen sulfide is not necessary to effect the desired catalytic action of lead acetate. In fact, as hereinafter indicated in a specific example, it is preferred to conduct the reaction of the hydrocarbon charge stock with hydrogen in the absence of added hydrogen sulfide. The process may be effected as a batch-type operation, or in a continuous manner in either upward flow or downward flow. The normally liquid hydrocarbons are separated from the total reaction zone product effiuent by any suitable means,

for example, through the utilization of a centrifuge, or

settling tanks, the remaining metal-containing sludge being treated as hereinafter set forth.

The metal-containing sludge is a viscous fluid consisting of the catalyticaly active metallic component, originally dispersed in the charge stock, unconverted asphaltenic material, soluble hydrocarbons, porphyrinic material containing nickel, vanadium, other metallic contaminants, coke and heavy carbonaceous material, etc. It has been found that the unconvetred asphaltenic material consists of from about 10.0% to about 20.0% by weight of the originally-present asphaltenes, which material is significantly more resistant to conversion, thereby causinng an inordinately large proportion of the difficulties experienced when the crude oil, or heavy fraction derived therefrom is subjected to hydrorefining and/ or hydrocracking. This asphaltenic material is that which possesses the tendency to become virtually immediately transformed into coke and gummy polymerization material, as a result of which the remaining portion of the asphaltenes fails to come into contact with the active catalyst components. It is, therefore, expedient and economical to remove about 10.0% to about 20.0% of the total asphaltenic material originally present in the hydrocarbon charge stock, from the catalyst-containing sludge, prior to recirculating the same to combine with the fresh hydrocarbon charge stock. Furthermore, the active catalytic component may then be recombined with the charge stock, forming thereby a colloidal suspension or dispersion, and effecting additional refining of the charge stock.

Following the separation of the normally liquid hydrocarbons from the catalyst-containing sludge, the latter is treated with a suitable organic solvent for the purpose of dissolving residual organic-soluble material such as pentane-soluble hydrocarbon products resulting from the conversion of the pentane-insoluble asphaltenic compounds. Any well-known organic solvent may be employed for the dissolution of the organic-soluble material in the sludge, and the resulting solution may be subjected to further reaction with hydrogen by recycling the same to combine with fresh hydrocarbon charge stock. The sludge will contain the original metallic components utilized as the catalyst, and, in addition thereto, at least a portion of lead and vanadium originally existing within the charge stock as organo-metallic complexes. Since these components, when colloidally dispersed within the charge stock exhibit an acceptable degree of catalytic activity, very little fresh catalyst is necessary to maintain catalytic activity, and in many instances the catalyst may be considered as self-sustaining.

The following example is given to illustrate the process of the present invention, and the effectiveness thereof in converting pentane-insolnble asphaltenes, while simultaneously effecting the conversion of snlfurous and nitrogenous compounds into sulfur-free and nitrogen-free hydrocarbons. It is not intended to limit the present in vention to the method, catalyst, charge stock and/or operating conditions employed in this illustration.

Example The hydrocarbon charge stock was the sour Wyoming crude oil having a gravity, API at 60 F., of 23.2 and containing 2,650 p.p.m. of nitrogen, 2.8% by weight of sulfur and 8.3% by Weight of pentane-insoluble asphaltenes. 500 grams of the Wyoming sour crude was admixed with an isobutyl alcohol solution containing 20.0 grams of lead acetate. The alcohol solution wasadded to the crude oil in dropwise fashion, the alcohol being distilled during the addition period. Following the formation of the colloidal suspension of lead acetate, the mixture was further distilled to remove gasoline hydrocarbons boiling at a temperature below about 400 F.; there remained a total of 417 grams of the topped crude oil containing lead acetate.

The mixture was placed in an 1,800-milliliter rotating autoclave, initially pressured to atmospheres with hydrogen, and then heated to a temperature of 400 C., the final pressure being about 200 atmospheres. These conditions were maintained for a period of .four hours, after which the contents of the autoclave were allowed to cool, the autoclave was depressured and the contents subjected to centrifugal separation to remove the metalcontaining sludge from the normally liquid hydrocarbon product. Upon analysis, the liquid hydrocarbon product indicated a gravity, API at 60 F., of 30.3, and contained 570 p.p.m. of nitrogen, 0.57% by Weight of sulfur and only 0.99% by weight of pentane-insoluble asphaltenes. When the same colloidal suspension was pressured to ten atmospheres with hydrogen sulfide, then to 100 atmospheres with hydrogen, prior to heating to a temperature of 400 C., the resulting normally liquid product effluent continued to be contaminated by more than 2.0%

by weight of sulfur and 2.0% material.

The foregoing specification and example clearly illustrate the method by which the present invention is effected, and the benefits to be alforded through the utilization thereof. The normally liquid hydrocarbon product is substantially free from asphaltenic material, and has been significantly decreased with respect to the concentration of sulfurous and nitrogenous compounds. It will be readily recognized by those possessing skill within the art of petroleum refining processing and particularly the hydrorefining of contaminated hydrocarbon charge stocks, that the product efiluent is highly suited for further processing in contact with a fixed-bed of solid catalyst particles to produce an ultra-clean hydrocarbon product substantially free from nitrogenous and sulfurous compounds.

We claim as our invention:

1. A process for hydrorefining a hydrocarbon charge stock which comprises colloidally dispersing in said charge stock a lead salt of an acid selected from the group consisting of fatty acids, polyfunctional acids and aromatic acids, reacting the resulting dispersion with hydrogen at a temperatures above about 225 C., removing a metalcontaining sludge from the reaction efiluent and rec-overing a hydrorefined liquid product.

2. A process for hydrorefining a hydrocarbon charge stock which comprises colloidally dispersing lead acetate in said charge stock, reacting the resulting dispersion with by weight of asphaltenic hydrogen at a temperature above about 225 C., removing a metal-containing sludge from the reaction efliuent and recovering a hydrorefined liquid product.

3. A process for hydrorefining a hydrocarbon charge stock which comprises colloidally dispersing lead acetate in said charge stock, reacting the resulting dispersion with hydrogen at a temperature of from about 225 C. to about 500 C. and at a pressure within the range of from about 500 to about 5,000 p.s.i.g., removing a metal-containing sludge from the reaction efiiuent and recovering a hydrorefined liquid product.

4. The process of claim 3 further characterized in that said charge stock is admixed with from about 1.0% to about 30.0% by weight of lead acetate, calculated as elemental lead.

5. The process of claim 3 further characterized in that said mixture is reacted with hydrogen in the absence of added hydrogen sulfide.

References Cited by the Examiner UNITED STATES PATENTS 3,113,986 12/1963 Breslow et a1. 252-431 3,134,796 5/ 1964 Kobetz 252-431 3,218,300 11/1965 Kullmar et al. 252-421 DELBERT E. GANTZ, Primary Examiner. SAMUEL P. JONES, Examiner. 

1. A PROCESS FOR HYDROREFINING A HYDROCARBON CHARGE STOCK WHICH COMPRISES COLLOIDALLY DISPERSING IN SAID CHARGE STOCK A LEAD SALT OF AN ACID SELECTED FROM THE GROUP CONSISTING OF FATTY ACITS, POLYFUNCTIONAL ACIDS AND AROMATIC ACIDS, REACTING THE RESULTING DISPERSION WITH HYDROGEN AT A TEMPERATURES ABOVE ABOUT 225*C., REMOVING A METALCONTAINING SLUDGE FROM THE REACTION EFFLUENT AND RECOVERING A HYDROREFINED LIQUID PRODUCT. 